IRCT2017052825732N15 IRCT 2017-06-01 Vice Chancellor for Research and Technology, Semnan University of Medical Sciences The effect of Low-dose aspirin on cervical length as an indicator of preterm delivery in nulliparous pregnant women that has been referred to gynecology clinic in Semnan The effect of Low-dose aspirin on cervical length as an indicator of preterm delivery in nulliparous pregnant women that has been referred to gynecology clinic in Semnan 2016-10-21 anticipated 60 Complete https://irct.ir/trial/21491 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Prevention. 3 Preterm labour. Intervention 1: Interventions group: 80 mg of aspirin daily (bedtime) in combination with folic acid + iron tablets from the second trimmest will be prescribed to patients To apply rigorous random assignment, in the first drugs by anyone other than researcher was placed in special packages and packages are labeled with A and B tag. Participants will start to taking experimental drug and up to 32 weeks of pregnancy (based on medical ultrasound) to continue taking medicine. These people will be examined to using the history and physical examination by researchers plan periodically. The cervical length (using the transvaginal ultrasound method) and also blood hemoglobin (using the complete blood counter in laboratory of Amiralmomenin hospital in Semnan) once a time at 13 weeks and once again at 30 weeks of pregnancy (based on medical ultrasound) will be measured. During periodical examination of pregnancy, the outcome measures are extracted from patients medical records and be recorded in the relevant forms. Intervention 2: Controls group: Daily folic acid with placebo (Consisting of sugar and starch that the shape, size and color is quite similar to aspirin) + iron tablets will be prescribed to patients.